1. Field of the Invention
The present invention relates in general to wireless communications systems and, more particularly, to a system and method for detecting unauthorized use of a mobile station in a wireless telecommunications system.
2. Description of the Related Art
With the increased popularity of wireless telecommunications systems (e.g., wireless cellular telecommunications systems), telecommunication service providers offer many different types of telecommunication services to their respective customers. Such services are generally provided to users on a subscription basis and, therefore, such users are generally referred to as "subscribers."
With the increase in overall usage of such wireless telecommunications systems, the incidence of fraudulent and unauthorized usage has also increased at an alarming rate. For example, it is estimated that fraudulent calls in the U.S. make up as much as 5 percent to 30 percent of all calls completed and account for hundreds of millions of dollars in lost revenue to telecommunication service providers. In addition to lost revenue, the effect of such wireless fraud also includes degraded service to the subscriber base, increased operational costs and reduced network capacity due to excess traffic associated with fraudulent calls.
There are several different methods by which unscrupulous persons attempt to obtain fraudulent access to and initiate unauthorized calls within a wireless telecommunications system. As a result of the mobile nature of mobile stations (e.g., cellular telephones), many of these methods of committing wireless fraud are extremely difficult to detect and prevent.
One such method of committing wireless fraud is known as "cloning fraud." Cloning fraud typically involves the misappropriation of a valid set of subscriber identification numbers (e.g., mobile identification number (MIN) and electronic serial number (ESN)) and programming the misappropriated MIN/ESN into at least one mobile station. When the "cloned" mobile station is fraudulently used to initiate calls over the wireless telecommunications network, the network, believing the unauthorized user to be the valid subscriber whose MIN/ESN was misappropriated, is deceived into providing such wireless services to the unauthorized user.
To combat wireless fraud, telecommunications service providers have resorted to a number of fraud detection and prevention systems. For instance, one proposed solution to identify cloning fraud involves the collection of call detail records associated with calls completed in the wireless network to identify concurrent call originations or receptions for a single subscriber identification number (MIN). Another proposed solution also includes the collection of call detail records associated with calls actually completed in the wireless network to determine whether the time interval between successive calls for a particular subscriber identification number (MIN) is too short to justify the geographic separation of the subscriber's mobile station for the successive calls. In yet another proposed solution, a subscriber's past calling activity is collected to formulate a historical usage pattern and any calls initiated by the subscriber that deviate from the historical usage pattern are identified as potentially fraudulent. Still another proposed solution performs a velocity check to identify potential cloning fraud by comparing the number of calls initiated by a subscriber within a discrete period of time to a minimum threshold number indicative of fraud.
A shortcoming of these conventional fraud detection systems is that they cannot identify such wireless fraud (e.g., cloning fraud) until after the fraudulent activity has occurred. That is, these conventional fraud detection systems generally require that the unauthorized user have actually placed the fraudulent call before the wireless fraud can be detected.